Problem with 'make distcheck'

[Sebastian Huber]

Hello,
in a 'lib' directory I have the following Makefile.am:

lib_LTLIBRARIES = libTACOExtensions.la

libTACOExtensions_la_SOURCES = $(top_srcdir)/server/src/TACOServer.cpp \
        $(top_srcdir)/common/src/TACOException.cpp \
        $(top_srcdir)/common/src/TACOExtensions.cpp \
        $(top_srcdir)/client/src/TACOClient.cpp
libTACOExtensions_la_LDFLAGS = -version-info $(subst .,:,@VERSION@) 
-export-dynamic
libTACOExtensions_la_LIBADD = $(LIB_TACO)

A 'make distcheck' fails due to 'Error: files left after distclean'. These 
files are

$find taco-ext-0.0.0/\=build/
taco-ext-0.0.0/=build/
taco-ext-0.0.0/=build/lib
taco-ext-0.0.0/=build/client
taco-ext-0.0.0/=build/client/src
taco-ext-0.0.0/=build/client/src/TACOClient.cpp
taco-ext-0.0.0/=build/client/python
taco-ext-0.0.0/=build/client/include
taco-ext-0.0.0/=build/common
taco-ext-0.0.0/=build/common/res
taco-ext-0.0.0/=build/common/src
taco-ext-0.0.0/=build/common/src/TACOException.cpp
taco-ext-0.0.0/=build/common/src/TACOExtensions.cpp
taco-ext-0.0.0/=build/common/include
taco-ext-0.0.0/=build/server
taco-ext-0.0.0/=build/server/src
taco-ext-0.0.0/=build/server/src/TACOServer.cpp
taco-ext-0.0.0/=build/server/include

exactly the source files of the library. Why are these files in the build 
directory?

Ciao